Production of dibenzanthrone



Patented Mar. 15, 1932 LLOYD C. DANIELS AND HERBERT 3'. WEST,

PATENT, OFFICE' or cnnr'ron, rnnnsxilvanm, ASSIGNORS TO THE SELDEN COMPANY, OF PITTSBURGH, PENNSYLVANIA; A CORPORATION OF 1 DELAWARE PRODUCTION or nriannzan'rnaonn 1 No Drawing.

" in the fusions is very high, amounting normally to from ten to twelve times the tl1eoretical amount required to react. The large excess has been necessary in order to produce a satisfactorily fluid melt. In the case of the isodibenzanthrone fusion a large excess of alkali over that theoretically required has also been necessary because of the low boiling point of alcohol which necessitated a large excess in order to maintain sufficient alcohol in the liquid state in the melt. The excess alcohol has to be recovered and this recovery is not complete. The prior processes for making dibenzanthrone also produced large amounts of impurities, the normal yield of dye being not more than based on the benzanthrone used, which not only means a loss of benzanthrone but also increases the cost of transforming dibenzanthrone into the nitrocompound in which form it is usually sold.

According to the present invention dibenzanthrone fusions are carried out in the presence of polymerized aliphatic aldehydes such as, for instance, trioxymethylene, paraldehyde, etc. When the reducing agents of the present invention are used a much smaller amount is generally suflicient, and the amount of caustic potash can also be decreased in many cases. The products obtained show higher percentages of dye than is obtainable in the prior processes, and a smoother, more satisfactory fusion is obtained.

The following specific examples give a few typical embodiments of the present invention, which, however, is in no sense restricted to the Application filed January 26, 1931. Serial No. 511,442..

details therein set forth. -It sl1ould be noted in particular that the invention is not limited to fusions inwhich the'amount of caustic potash is decreased. Insome cases it. is desirable to use larger amounts of caustic potash and to obtain only the advantages of higher purity of product. Such processes are, of course, included in the present invention, as Well as those in which the advantages of improved yield are combined with areduction inthe amount of caustic potashused.

Ezvample 1; g v V 100 parts of benzanthrone, by weight, are ground with 5 parts of trioxymethylene and added slowly at 220 C. to a mixture of 300 parts of 85-95% causticpotash and 2 parts of trioxymethylene. After the addition of the benzanthrone the mixture isheated to 230-240- C. for d5 minutes, after which the dibenzanthrone is isolated by pouring the melt intowater, oxidizing-the leuco compound with air and filtered in the usual manner. The product obtained is of superior quality, giving brighter and stronger dyeings, and the yield is better than when dextrin is used in the standard fusion. A saving is also effected by the reduction in amount of caustic potash employed. j

. Example 2 100 parts of benzanthrone, by'weight, are ground together with 5'00 8 parts of paraldehyde and added slowly at 220 C. to a mixture of 300 parts of 8595% caustic potash and from 26 parts of paraldehyde or trioxymethylene. After adding the benzanthrone, the mixture is heated to complete the fusion, as described in Example 1, an excel lent dibenzanthrone compound being obtained.

Ewample 3 100 parts of chlorbenzanthrone, by weight, are fused in a mixture containing 300 parts of 85-95% KOH and 120 parts of trioxymethylene and 100 parts of alcohol. The fusion is carried out under a reflux condenser at the boiling point of the mixture, and excellent yields of isodibenzanthrone are obtained.

Better yields are obtained than When alcohol is used alone as a reducing agent, and the amount of caustic potash is smaller than that normally required.

What is claimed as new is:

1. A method of fusing a benzanthrone compound to produce a diloenzanthrone compound, which comprises fusing the benzanthrone compound with caustic alkali in the presence of a polymerized aliphatic aldehyde. 2. A method of fusingbenzanthrone to prod'uce'dibenzanthrone, which comprises fusing benzanthrone with caustic alkali in the presence of a polymerized aliphatic aldehyde. v 3. A method of fusing chlorbenzanthrone to produce isodibenzanthrone, which comprises fusing the benzanthrone compound with caustic alkali and alcohol in the presence of a polymerized aliphatic aldehyde.

4. A method of fusing chlorbenzanthrone to produce isodibenzanthrone, which comprises fusing the benzanthrone compound with caustic alkali in the presenoe of a polymerized aliphatic aldehyde and an amount s; of alcohol less than that normally used in fusionof chlorbenzanthrone with alcohol as the sole reducing agent.

5. A method of fusing a benzanthrone compound to produce a dibenzanthrone com- ;gg; pound, which comprises fusing the benzanthrone compound with caustic alkali in the presence of trioxymethylene.

' 6. A method of fusing benzanthrone to produce dibenzanthrone, which comprises 1; fusing benzanthrone with caustic alkali in the presence of trioxymethylene. V

7. A method of fusing chlorbenzanthrone to produce isodibenzanthrone, which com- 7 prises fusing the benzanthrone compound 46 with caustic alkali and alcohol inthe presence of trioxymethylene.

8. A method of fusing chlorbenzanthrone to produce isodibenzanthrone, which comprises fusing the benzanthronev compound with caustic alkali in the presence of trioxymethylene and an amount of alcohol less than thatnormally used in fusion of chlorbenza-nthrone with alcohol as the sole reducing agent.

Signed at Pittsburgh, Pennsylvania, this 50 23rd dayof January, 1931.

'- LLOYD C. DANIELS.

HERBERT J. -WEST. 

